Extracellular Enzyme Activities and Carbon/Nitrogen Utilization in Mycorrhizal Fungi Isolated From Epiphytic and Terrestrial Orchids

Fungi employ extracellular enzymes to initiate the degradation of organic macromolecules into smaller units and to acquire the nutrients for their growth. As such, these enzymes represent important functional components in terrestrial ecosystems. While it is well-known that the regulation and efficiency of extracellular enzymes to degrade organic macromolecules and nutrient-acquisition patterns strongly differ between major fungal groups, less is known about variation in enzymatic activity and carbon/nitrogen preference in mycorrhizal fungi. In this research, we investigated variation in extracellular enzyme activities and carbon/nitrogen preferences in orchid mycorrhizal fungi (OMF). Previous research has shown that the mycorrhizal fungi associating with terrestrial orchids often differ from those associating with epiphytic orchids, but whether extracellular enzyme activities and carbon/nitrogen preference differ between growth forms remains largely unknown. To fill this gap, we compared the activities of five extracellular enzymes [cellulase, xylanase, lignin peroxidase, laccase, and superoxide dismutase (SOD)] between fungi isolated from epiphytic and terrestrial orchids. In total, 24 fungal strains belonging to Tulasnellaceae were investigated. Cellulase and xylanase activities were significantly higher in fungi isolated from terrestrial orchids (0.050 ± 0.006 U/ml and 0.531 ± 0.071 U/ml, respectively) than those from epiphytic orchids (0.043 ± 0.003 U/ml and 0.295 ± 0.067 U/ml, respectively), while SOD activity was significantly higher in OMF from epiphytic orchids (5.663 ± 0.164 U/ml) than those from terrestrial orchids (3.780 ± 0.180 U/ml). Carboxymethyl cellulose was more efficiently used by fungi from terrestrial orchids, while starch and arginine were more suitable for fungi from epiphytic orchids. Overall, the results of this study show that extracellular enzyme activities and to a lesser extent carbon/nitrogen preferences differ between fungi isolated from terrestrial and epiphytic orchids and may indicate functional differentiation and ecological adaptation of OMF to local growth conditions.

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Response of Nodularia spumigena to pCO2 – Part 2: Exudation and extracellular enzyme activities

Biogeosciences ◽

10.5194/bg-10-567-2013 ◽

2013 ◽

Vol 10 (1) ◽

pp. 567-582 ◽

Cited By ~ 22

Author(s):

S. Endres ◽

J. Unger ◽

N. Wannicke ◽

M. Nausch ◽

M. Voss ◽

...

Keyword(s):

Alkaline Phosphatase ◽

Organic Matter ◽

Enzyme Activities ◽

Extracellular Enzymes ◽

Extracellular Enzyme ◽

High Pco2 ◽

Nodularia Spumigena ◽

Extracellular Enzyme Activities ◽

Pco2 Treatment ◽

Co2 Concentrations

Abstract. The filamentous and diazotrophic cyanobacterium Nodularia spumigena plays a major role in the productivity of the Baltic Sea as it forms extensive blooms regularly. Under phosphorus limiting conditions Nodularia spumigena have a high enzyme affinity for dissolved organic phosphorus (DOP) by production and release of alkaline phosphatase. Additionally, they are able to degrade proteinaceous compounds by expressing the extracellular enzyme leucine aminopeptidase. As atmospheric CO2 concentrations are increasing, we expect marine phytoplankton to experience changes in several environmental parameters, including pH, temperature, and nutrient availability. The aim of this study was to investigate the combined effect of CO2-induced changes in seawater carbonate chemistry and of phosphate deficiency on the exudation of organic matter, and its subsequent recycling by extracellular enzymes in a Nodularia spumigena culture. Batch cultures of Nodularia spumigena were grown for 15 days under aeration with low (180 μatm), medium (380 μatm), and high (780 μatm) CO2 concentrations. Obtained pCO2 levels in the treatments were on median 315, 353, and 548 μatm CO2, respectively. Extracellular enzyme activities as well as changes in organic and inorganic compound concentrations were monitored. CO2 treatment–related effects were identified for cyanobacterial growth, which in turn influenced the concentration of mucinous substances and the recycling of organic matter by extracellular enzymes. Biomass production was increased by 56.5% and 90.7% in the medium and high pCO2 treatment, respectively, compared to the low pCO2 treatment. In total, significantly more mucinous substances accumulated in the high pCO2 treatment, reaching 363 μg Xeq L−1 compared to 269 μg Xeq L−1 in the low pCO2 treatment. However, cell-specific rates did not change. After phosphate depletion, the acquisition of P from DOP by alkaline phosphatase was significantly enhanced. Alkaline phosphatase activities were increased by factor 1.64 and 2.25, respectively, in the medium and high compared to the low pCO2 treatment. We hypothesise from our results that Nodularia spumigena can grow faster under elevated pCO2 by enhancing the recycling of organic matter to acquire nutrients.

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Response of Nodularia spumigena to pCO2 – Part 2: Exudation and extracellular enzyme activities

Biogeosciences Discussions ◽

10.5194/bgd-9-5109-2012 ◽

2012 ◽

Vol 9 (4) ◽

pp. 5109-5151 ◽

Cited By ~ 5

Author(s):

S. Endres ◽

J. Unger ◽

N. Wannicke ◽

M. Nausch ◽

M. Voss ◽

...

Keyword(s):

Alkaline Phosphatase ◽

Organic Matter ◽

Enzyme Activities ◽

Extracellular Enzymes ◽

Extracellular Enzyme ◽

Marine Phytoplankton ◽

High Pco2 ◽

Nodularia Spumigena ◽

Extracellular Enzyme Activities ◽

Pco2 Treatment

Abstract. The filamentous and diazotrophic cyanobacterium Nodularia spumigena plays a major role in the productivity of the Baltic Sea as it forms extensive blooms regularly. Under phosphorus limiting conditions Nodularia spumigena has a high enzyme affinity for dissolved organic phosphorus (DOP) by production and release of alkaline phosphatase. Additionally, it is able to degrade proteinaceous compounds by expressing the extracellular enzyme leucine aminopeptidase. As atmospheric CO2 concentrations are increasing, we expect marine phytoplankton to experience changes in several environmental parameters including pH, temperature, and nutrient availability. The aim of this study was to investigate the combined effect of CO2-induced changes in seawater carbonate chemistry and of phosphate deficiency on the exudation of organic matter, and its subsequent recycling by extracellular enzymes in a Nodularia spumigena culture. Batch cultures of Nodularia spumigena were grown for 15 days aerated with three different pCO2 levels corresponding to values from glacial periods to future values projected for the year 2100. Extracellular enzyme activities as well as changes in organic and inorganic compound concentrations were monitored. CO2 treatment–related effects were identified for cyanobacterial growth, which in turn was influencing exudation and recycling of organic matter by extracellular enzymes. Biomass production was increased by 56.5% and 90.7% in the medium and high pCO2 treatment, respectively, compared to the low pCO2 treatment and simultaneously increasing exudation. During the growth phase significantly more mucinous substances accumulated in the high pCO2 treatment reaching 363 μg Gum Xanthan eq l−1 compared to 269 μg Gum Xanthan eq l−1 in the low pCO2 treatment. However, cell-specific rates did not change. After phosphate depletion, the acquisition of P from DOP by alkaline phosphatase was significantly enhanced. Alkaline phosphatase activities were increased by factor 1.64 and 2.25, respectively, in the medium and high compared to the low pCO2 treatment. In conclusion, our results suggest that Nodularia spumigena can grow faster under elevated pCO2 by enhancing the recycling of organic matter to acquire nutrients.

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ISOLATE ENDOPHYTIC FUNGI FROM LOCAL CATHARANTHUS ROSEUS AND ANALYZE THEIR EXTRACELLULAR ENZYME ACTIVITIES

International Journal of Advanced Research ◽

10.21474/ijar01/12896 ◽

2021 ◽

Vol 9 (5) ◽

pp. 702-708

Author(s):

Nguyen Chi Mai ◽

◽

Pham Thi Hoe ◽

Vu Huong Giang ◽

Le Quynh Lien ◽

...

Keyword(s):

Endophytic Fungi ◽

Catharanthus Roseus ◽

Fusarium Solani ◽

Enzyme Activities ◽

Extracellular Enzymes ◽

Extracellular Enzyme ◽

Activity Analysis ◽

Coastal Regions ◽

Natural Sources ◽

Extracellular Enzyme Activities

Endophytic microbia are known as natural sources for producing valuable enzymes. In this study, four endophytic fungi were isolated from roots of local Catharanthus roseus (L.) G. Don var. roseus (purple flower) and C. roseus var. ocellatus (red stamens white flower) widely grown in Nha Trang. They were identified as Fusarium solani RN1, Chaetomium funicola RN3, Penicillium rugulosum RN4 and Chaetomium homopilatum WN1 based on morphologies colonies and spores. The activity analysis of their extracellular enzymes indicted all isolated endophytic fungi are able to produce protease, cellulose, xylanase as well as amylase. This is the first report on the endophytic fungi inhabited in C. roseus plant growing in the coastal regions of Vietnam, which could provide an attractive source for bioactive enzyme exploitation.

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Effects of Canada Goldenrod Invasion on Soil Extracellular Enzyme Activities and Ecoenzymatic Stoichiometry

Sustainability ◽

10.3390/su13073768 ◽

2021 ◽

Vol 13 (7) ◽

pp. 3768

Author(s):

Zhiyuan Hu ◽

Jiating Li ◽

Kangwei Shi ◽

Guangqian Ren ◽

Zhicong Dai ◽

...

Keyword(s):

Nutrient Cycling ◽

Enzyme Activities ◽

Extracellular Enzymes ◽

Extracellular Enzyme ◽

Enzymatic Activities ◽

Rapid Expansion ◽

Vegetation Diversity ◽

Alien Plant ◽

Extracellular Enzyme Activities ◽

Extracellular Enzymatic Activities

The rapid expansion of Canada goldenrod (Solidago canadensis L.) in China has drawn considerable attention as it may not only decrease vegetation diversity but also alter soil nutrient cycling in the affected ecosystems. Soil extracellular enzymes mediate nutrient cycling by catalyzing the organic matter decomposition; however, the mechanisms by which alien plant invasion may affect soil extracellular enzymes remain unclear. The objective of this study was to investigate the responses of soil extracellular enzyme activities and ecoenzymatic stoichiometry to S. canadensis invasion. Several extracellular enzymatic activities related to carbon, nitrogen, and phosphorus cycling were measured using a fluorometric method. Ecoenzymatic stoichiometry was used as a proxy of soil microbial metabolic limitations. S. canadensis invasion appeared to be associated with decreased activities of enzymes and with substantial conversions of microbial metabolic carbon and nitrogen limitations. The changes in the activities of extracellular enzymes and the limitations of microbial metabolism were correlated with the alterations in the nutrient availability and resource stoichiometry in the soil. These findings reveal that the alterations in soil available nutrients associated with S. canadensis invasion may regulate extracellular enzymatic activities and cause microbial metabolic limitations, suggesting that S. canadensis invasion considerably affects biogeochemical cycling processes.

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